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#include<stdio.h>
#include<string.h>
#include<vector>
#include<queue>
#include<stdlib.h>
using namespace std;
const int N=208;
const int MAX=0x7fffffff;
int dist[N];
int n,flag;
struct Edge
{
int to,val;
Edge(int a=0,int b=0):to(a),val(b) {}
bool operator <(const Edge &a)const
{
if(val==a.val)return to<a.to;
return val>a.val;
}
};
vector<Edge>v[N];
void dijkstra(int s)
{
memset(dist,0x3f,sizeof(dist));
flag=dist[0];
dist[s]=0;
priority_queue<Edge>q;
q.push(Edge(s,0));
while(!q.empty())
{
Edge top=q.top();
q.pop();
for(int i=0; i<v[top.to].size(); i++)
{
Edge tmp=v[top.to][i];
if(dist[tmp.to]>top.val+tmp.val)
{
dist[tmp.to]=top.val+tmp.val;
q.push(Edge(tmp.to,dist[tmp.to]));
}
}
}
}
int main()
{
int i,j,k,x,y,num;
int s,t;
while(scanf("%d%d%d",&num,&s,&t)!=EOF)
{
if(!num&&!s&&!t)return 0;
n=0;
for(int i=0; i<=N; i++)v[i].clear();
for(int i=0; i<num; i++)
{
int floor,exc[160];
scanf("%d",&floor);
for(int j=0; j<floor; j++)
{
scanf("%d",&exc[j]);
if(exc[j]>n) n=exc[j];
for(int vv=0; vv<j; vv++)
{
v[exc[j]].push_back(Edge(exc[vv],abs(exc[vv]-exc[j])));
v[exc[vv]].push_back(Edge(exc[j],abs(exc[vv]-exc[j])));
}
}
}
dijkstra(s);
printf("%d
",dist[t]);
}
}